This invention relates to flow control apparatus for providing switching of fluid flow among multiple flow conduits, and more particularly relates to valve control devices for selective fluid flow switching.
Valve systems which have been developed for providing cycled switching between multiple fluid processing units such as dual molecular sieve beds for oxygen separation from air, have employed solenoid or electro-pneumatic operated valves with electronic circuits for timing of the cycled valve action. For example, in conventional medical oxygen concentrator systems, (such as the portable oxygen concentrator devices commercially produced by Puritan-Bennett Corporation and Smith & Davis Company) multiple solenoid valves switch compressed air flow back and forth between the two oxygen separating sieve beds so that one bed is separating oxygen from the air while the other bed is being purged of the nitrogen, carbon dioxide and water vapor adsorbed on the molecular sieve material in order to regenerate the sieve material for further oxygen separation. The solenoid-operated valves not only require electronic circuitry for controlling the cycled valve action, but in addition, the instant open and close action of the solenoid operated spindle valves create substantial shock and noise caused by sudden acceleration and deceleration of the valve spindles, and the handling of air and air component flow, as well as channeling and abrasion of the sieve bed particles by the resulting pneumatic impacts.
These disadvantages are eliminated in the valve and fluid flow switching system in accordance with the present invention.